Toilet seat and lid assembly

ABSTRACT

A toilet seat and lid, each comprising a rigid insert injection molded of thermoplastic material. Each insert is then over-molded by injection molding with a thermoplastic elastomeric material which provides the outer surface of the seat and lid. The inserts are dimensioned with respect to their over-molded surfaces to be smaller than the finished seat and lid and are designed to give maximum strength to the seat and lid. Each insert is shaped to promote the flow of the over-mold material and to minimize shrinking, swelling or distortion of the insert. The elastomeric material is preferably chemically compatible with the inserts to allow a chemical as well as a mechanical bond to take place. The over-molded material provides the desired soft, non-slip, warm to the touch outer characteristics of the seat and lid.

This application is a continuation-in-part Of U.S. patent applicationSer. No. 09/089,469 filed on Jun. 2, 1998 that issued as U.S. Pat. No.6,154,892 on Dec. 5, 2000.

TECHNICAL FIELD

The invention relates to a seat and lid assembly for a toilet, and moreparticularly to such a seat and lid compromising injection molded,reinforced plastic inserts injection over-molded with a chemicallycompatible material which provides the desired outer surfacecharacteristics of the seat and lid.

BACKGROUND ART

The invention is directed to the improvement of the feel and comfort ofa toilet seat and lid, and to the provision of a comfortable, warm,non-slip seating surface. This is accomplished by utilizing modernthermoplastic material and high-pressure injection molding techniques.While not intending to be so limited, the invention will be described inits application to a toilet seat and lid. It will be understood that thebasic teachings of the present invention can be applied to toilet seatswithout lids and other types of seats.

Prior art workers have devised many types of toilet seats and lids toimprove the comfort, look and convenience thereof Heretofore toiletseats and lids have been constructed from rigid materials such as woodor plastic, or made from a solid core upholstered in foam padding and/ora vinyl covering. Typical rigid plastic or wood seats are relativelycold to the touch and slippery. Upholstered seats and lids, with orwithout padding, are not particularly durable and are susceptible tocuts and tears. Additionally some people find the feel of padded vinylseats and lids to be undesirable. Prior art workers have molded amaterial over another material in an attempt to hide imperfections in athick part but still produce a hard rigid seat that does not address theissues of comfort and non slip characteristics. Prior art workers havealso attempted to produce a padded, resilient-type seat usingcomplicated and costly molding methods employing catalyzed materialssuch as urethane. Molding a seat by using catalyzed low pressurematerials requires time-consuming mixing and pouring, resulting in lessthan satisfactory results and a costly product.

The present invention is based upon the discovery that a seat and lidassembly comprising inserts of reinforced thermoplastic material, withover-molded thermoplastic material which determines the characteristicsof the outer surface of the seat and lid, can overcome the above notedproblems. There are six Shore scales that are used to measure thehardness of synthetic materials. They are as follows: Shore A, Shore B,Shore C, Shore D, Shore DO and Shore OO. All of the scales range from0-100. The most commonly used scales are Shore A and Shore D. There isno direct conversion between the different scales. An example of anapproximate comparison would be (Shore A 50=Shore B 30-35=Shore C20=Shore D 10-15). Another example of approximate comparison would be(Shore A 100=Shore B 85=Shore C 65=Shore D 45). The preferredpolypropylene material used for the insert has a hardness ofapproximately Shore D 70. When a thermoplastic elastomeric material witha Shore A durometer of 90 or below is used as the over-mold material,the seat and lid are provided with a soft, comfortable, durable surfacewhich will not tear and which have non-slip characteristics, which,nevertheless, allows reasonable mobility while using the seat. Thethermoplastic elastomeric material should not have a durometer hardnessgreater than Shore D50. Some synthetic materials have a durometerhardness that would be measured on the Shore A scale. Harder syntheticmaterials would be measured on the Shore D scale. The elastomer providesa completely different and arguably superior feel as compared toconventional seats and padded seats. The seat of the present inventionis not padded and does not deform when sat upon. The surface alsoprovides an aesthetically pleasing finish which is easily cleaned and isavailable in many colors.

It is an object of the present invention to provide an injection moldedtoilet seat and lid which are soft to the touch and relatively warm andnon-slip as compared to a conventional hard seat and lid.

It is an object of the present invention to provide a toilet seat andlid with the above features which are both strong and durable.

It is an object of the present invention to provide a toilet seat andlid with the above features which are easy to clean.

It is an object of the present invention to provide a more comfortableand non-slip toilet seat and lid assembly, than is achievable withexisting designs and conventional construction techniques.

It is an object of the present invention to provide a seat and lid withantimicrobial qualities.

Finally, it is an object of the invention to provide a soft feelinginjection molded toilet seat shaped to fit the user comfortably.

DISCLOSURE OF THE INVENTION

According to the invention there is provided a strong, durable,comfortable toilet seat and lid assembly which is non-slip and easy toclean. The assembly comprises rigid inserts molded of a reinforcedthermoplastic material. The inserts are over-molded with a thermoplasticmaterial which provides them with the desired surface characteristics.

The inserts are precisely dimensioned so that their areas to beover-molded are smaller than the finished seat. The inserts are designedto give maximum strength to the seat and lid and are shaped to promotethe flow of the over-mold material to minimize flowjoint or flow weldproblems, to be described hereinafter. Each insert is designed tominimize shrinking, swelling or distortion thereof and, to this end, canbe provided with strategically located ribs and appropriate cored areas.

When the thermoplastic material of the inserts and the over-moldmaterial elastomer are both of the same chemical base, the over-moldwill bond both mechanically and chemically with the inserts and willprovide the seat and lid with a soft, comfortable, non-slip surface. Thesurface may be smooth or textured to enhance the feel and appearance ofthe seat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an inside elevational view of the lid insert of the presentinvention.

FIG. 2 is a top plan view of a seat insert of the present invention.

FIG. 3 is an inside elevational view of an over-molded lid of thepresent invention.

FIG. 4 is a fragmentary cross-sectional view taken along section line4—4 of FIG. 3.

FIG. 5 is a top plan view of an over-molded seat of the presentinvention.

FIG. 6 is a fragmentary cross-sectional view taken along section line6—6 of FIG. 5.

FIG. 7 is a side elevational view of the lid and seat of FIGS. 3 and 5.

FIG. 8 is an elevational view of the upper surface of the lid of FIG. 7and the bottom surface of the seat of FIG. 7.

FIG. 9 is a cross-sectional view taken along section line 9—9 of FIG. 8.

FIG. 10 is a cross-sectional view taken along section line 10—10 of FIG.8.

FIG. 11 is a perspective view of the over-molded seat of the presentinvention together with the hinge elements by which it is hingedlyattached to the toilet bowl.

FIG. 12 is an exploded view illustrating the outside surface of the lidof the present invention and the bottom surface of the seat of thepresent invention.

FIG. 13 is a top plan view of a seat of the present invention providedwith areas or bands of texture.

FIG. 14 is a top plan view of the lid of the present invention providedwith areas or bands of texture.

FIG. 15 is a top plan view of a lid having a sculpture formed by theover-molding.

FIG. 16 is an exploded view of a lid and seat of the present inventionprovided with hinge elements which are embedded in the inserts thereof.

FIG. 17 is a bottom plan view of a seat of the present inventionprovided with a groove to receive a heating element. FIG. 18 is across-sectional view of a seat of the present invention provided with agroove and heating element therein covered by the over-mold material.

FIG. 18 is a cross-sectional view of a seat of the present inventionprovided with a groove and heating element therein covered by theover-mold material.

DETAILED DESCRIPTION OF THE INVENTION

It will be understood by one skilled in the art that, for each type ormodel of seat and lid to which the present invention is to applied, thefinished seat and lid, inserts and the molds must be appropriatelydesigned in accordance with the teaching of the present invention.

The exemplary seat and lid are each made of two major parts, (an insertand an over-mold), in two steps. In some embodiments additional partsmay be used such as hinges imbedded on or molded as part of the inserts,as will be described hereinafter. In the exemplary embodiment, the firststep is the injection molding of the strong substantially rigid,lightweight seat inserts. The inserts are best shown in FIGS. 1 and 2,and are generally indicated at 1 a and 1 b. The inserts 1 a and 1 bconstitute substantially the bulk of the finished seat and lid and serveas the skeleton of the over-molded seat 2 b and 2 a of FIGS. 3 and 5.The seat portion insert 1 b of FIG. 2 comprises a generally ovalstructure forming the shape of the seat, and is dimensioned to fit theparticular toilet for which it is designed. The seat may have anyappropriate shape including the well-known “C” shape, open-frontconfiguration. The lid insert 1 a is generally shaped in an oval toapproximate the shape of the finished lid 2 a. The rearward portions ofthe lid insert 1 a and the seat insert 1 b have either hinges 3 and 3 amolded as part of the inserts as shown in FIGS. 1 and 2, or hingesimbedded or otherwise appropriately attached to the inserts as shown inFIG. 16.

The inside surface of the lid insert 1 a is provided with four integralstand-offs constituting a one-piece part of insert 1 a and indicated at1 c, 1 d, 1 e, and 1 f. In a similar fashion, the bottom surface of theseat insert 1 b is provided with four integral stand-offs constituting aone-piece part of insert 1 b and indicated at 1 g, 1 h, 1 i and 1 j.

Inserts 1 a and 1 b are preferably molded of a strong, reinforced,synthetic material. Any appropriate synthetic material can be used aslong as it is chemically compatible with the over-molded material. Thesynthetic material of the inserts may include a reinforcing fillermaterial. Some examples of a reinforcing filler material are: 1) afiberglass reinforced, olefin base, thermoplastic material, 2) afiberglass reinforced polypropylene, 3) a fiberglass reinforcedpolypropylene containing from about 1% to about 2% of a foaming agent.When the preferred thermoplastic elastomer TPE) over-mold is used as isdescribed hereinafter, an olefin base thermoplastic material isnecessary for the insert because, under these circumstances, theover-mold material will chemically bond with the insert material. Whenthe injection molded seat insert comprises an olefin thermoplastic, theover-mold layer may comprise an olefin base thermoplastic elastomerchemically bonded to the injection molded seat insert. When theinjection molded seat insert comprises a fiberglass reinforcedpolypropylene, the over-mold layer may comprise an olefin basethermoplastic elastomer chemically bonded to the injection molded seatinsert. Excellent results have been achieved, for example, when specificformulations of polypropylene are used as the base reinforcing insert.The preferred high Crystalline, Homo-polymer polypropylene providesexcellent adhesion to compatible olefin elastomers as well as a highresistance to abnormal sinks and flow lines. This material, once cured,has a great scratch resistance and a higher flexural modulus thanco-polymer polypropylene. An example of such material is manufactured byHuntsman Corp of Salt Lake City, Utah and is identified as product#HOMPP-P4C6Z052.

The reinforced synthetic material can also be combined with anendothermic foaming agent. The foaming agent enables the molding ofthick, lightweight portions of the insert without visible “sink” areas,gross warping, or the like. In addition, the foaming agent helpsminimize or eliminate “joint” and “weld” problems. Welds, for example,are created when portions of molten plastic, traveling in differentdirections, meet in the mold and solidify. The insert mold must bedesigned in such a way to overcome this problem so that the weight of aperson sitting or standing on the seat will not cause a failure. Apreferred way to overcome or minimize flow joints or flow welds is tointroduce the material into the mold from one source through a singlegate, when possible. On the other hand, in accordance with conventionalmolding techniques, the sheer size of the seat would dictate theprovision of multiple sources of mold material and multiple gates toguarantee complete fill. Multiple sources and gates, however,potentially cause welds and joints. In the insert embodimentsillustrated in FIGS. 1 and 2, the joint and weld problems were overcomeby using the above noted endothermic foaming agent which, whenactivated, becomes solvent-like, thereby lowering the polymer viscosityduring the injection molding process for the inserts 1 and 1 a. Becauseof the reduced melt viscosity, molds can be made for the lid and seatinserts, each having a single gate resulting in the production of lidand seat inserts free of numerous polymer welds. With other seat designsand configurations multiple gates may be desired or required.

The foaming agent also enhances the inserts by creating essentially astructural “honeycomb” within the inserts themselves. Excellent resultshave been achieved with a foaming agent sold by Reedy International ofKeyport, N.J., under the trademark SAFOAM and the designation PE-50. Thefoaming agent constitutes from 1% to 2% of the syntheticmaterial-foaming agent combination.

The inserts are designed to give maximum strength to the finished seatand lid assembly. In addition, the inserts may be cored out in criticalthick areas to reduce warping, excessive swelling or other deformationof the insert.

As indicated above, each overall insert is precisely dimensioned so thatits areas to be over-molded are smaller than the finished seat. Thedimensions are chosen to minimize warpage of the insert and to allow forproper over-molding material flow and bonding.

Once inserts 1 a and 1 b are molded, the next step is to mount theinserts in final molds and injection mold (over-mold under heat andpressure) thereon the thermoplastic elastomer. As indicated above, thethermoplastic elastomeric material preferably should be chemicallycompatible with the material from which the inserts are molded so that achemical bond occurs between the synthetic material of the insert andthe thermoplastic elastomer of the over-mold. Excellent results havebeen provided, for example with a thermoplastic elastomer provided byAdvanced Elastomer Systems of St. Louis, Mo., under the trademarkSANTOPRENE.

An antimicrobial additive can be blended with the Santoprene to give theseat surface built-in antimicrobial characteristics. Excellent resultshave been achieved with an antibacterial additive provided by MortonInternational of Boston, Mass. under the designation Vinyzene.

The inside elevation view of FIG. 3 illustrates the over-molded lidinsert, generally indicated at 2 a. FIG. 5 is a top view of theover-molded seat insert, generally indicated at 2 b. FIG. 4 is afragmentary transverse cross-sectional view of the over-molded lid 2 ataken along section line 4—4 of FIG. 3. FIG. 6 is a fragmentarycross-sectional view taken along section line 6—6 of FIG. 5. FIG. 7 is aside elevational view and FIG. 8 is a view of the assembled over-moldedlid 2 a and over-molded seat 2 b illustrating the top surface of theover-molded lid 2 a.

In these figures, the thermoplastic rubber over-mold is generallyindicated at 10. The rearward most end of the lid and seat inserts areover-molded, with the exception of the hinge contact points as isclearly shown in FIGS. 3, 5 and 10. Generally, the entire exteriorsurfaces of inserts 1 a and 1 b are over-molded although on some designssome insert surfaces will be exposed. For example, in the preferredembodiment, ribs 11 a and 11 b, 11 c and 11 d are not over-molded (seeFIG. 8). In addition, each of the lid stand-offs 1 c, 1 d, 1 e and 1 fand each of the seat stand-offs 1 g, 1 h, 1 i and 1 j has a hole 12formed in the over-molding material thereon. These are clearly shown inFIGS. 3 and 8. The holes are formed by the molds for the over-moldingprocess which uses the stand-offs of the lid 2 a and 2 b as contactpoints for the mold elements which support the inserts 1 a and 1 b inthe over-mold molds. FIG. 9 is a cross-sectional view taken alongsection 9—9 of FIG. 8. The section line passes through stand-off 1 g andclearly shows the hole 12. FIG. 10 clearly shows that the hinge contactpoints are not over-molded.

Reference is made to FIGS. 10 and 11. These figures show the hingeelements 3 a of seat 2 b. The figures also illustrate an additionalhinge element 3 b for each hinge element 3 a by which the seat and lidare affixed to the toilet bowl. Each of the two hinge elements 3 b havea base portion 3 c and an upstanding hinge member 3 d. Each base portion3 c has a perforation 3 e formed therein enabling it to be bolted to thetoilet bowl. The hinge elements 3 b could comprise over-molded elementsexcept for the hinge contact faces. They could also simply comprisemetallic or plastic molded members. In FIG. 11 it is clear that thehinge element 3 a of seat 2 b lie just inside hinge elements 3 d. Whilethe lid 2 a and its hinge elements 3 are not shown in FIG. 11, it isevident from FIG. 5 that the lid hinge elements 3 will lie just outsidehinge elements 3 d. The hinge elements of each group of three 3, 3 d,and 3 a have coaxial perforations for the receipt of a hinge pin.

It will be understood that distortion considerations due to shrinkage,warpage, outside forces and the like are unique with respect to eachover-molded seat. The inserts 1 a and 1 b are first molded at whichpoint minimal shrinkage or warpage may occur and thereafter the insertcomponents become stabilized.

Next, the over-molding places a new thermoplastic material over thealready stabilized inserts creating stresses not found in single stagemolded parts, When the over-mold material is applied to the inserts withthe appropriate heat and pressure, and then allowed to cool andstabilize, shrinkage of the thermoplastic rubber will tend to warpcertain areas of the lid and seat.

Strategically placed ribs 11 a, 11 b, 11 c and 11 e, as shown in FIG.12, can be used to minimize or eliminate this distortion. Since thethermoplastic material of the insert and the thermoplastic rubber arecompatible, the materials will chemically bond under the heat andpressure of the injection molding operation.

Again it is desirable to prevent unsightly weld and joint lines in theover-mold material. In the exemplary embodiment of FIGS. 3 and 5, it ispossible to introduce the over-mold material into the mold through asingle gate approximately at 17. The ribs 11 a, 11 b, 11 c, 11 e and 13a, 13 b and 13 c of FIG. 12, and ribs 14 a, 14 b, 14 c and 14 d of FIG.2 (which are unique to each seat and lid) are designed and located tominimize the disturbance of the flow of the thermoplastic elastomer. Atthe same time, the flow path of the elastomer in the mold must becarefully designed to provide the most efficient elastomer-to-insertbonding.

Insert 1 b is also designed to provide a mechanical bond, whereverpossible, between the thermoplastic rubber and the insert. In areaswhere delamination would be most likely to occur, such as at thinfleeting edges of the insert, the insert is configured to cause thethermoplastic rubber to hook thereabout, forming a permanent melt seal.Such permanent melt seals are indicated at 15 in FIG. 6.

Because of the two-step injection molding process of the presentinvention, specific rheological analysis was made to ensurecompatibility between the two processes and to provide critical datasuch as linear and transverse shrinkage ratios, as well on thestructural strength, shrinkage, and warpage of the seat assembly.

During the injection molding of the insert 1 a, the reinforced syntheticmaterial was introduced into the mold at a point generally indicated inFIG. 1 at 16. This, of course, created a sprue which had to be removed.During the over-molding process the insert 1 a was supported in thesecond mold primarily by means on pins entering openings indicated at 12in FIG. 3 and also the seat supported by the nibs 11 a, 11 b, 11 c, and11 e. Again, a single gate was used, the gate being located at a pointgenerally indicated at 17 in FIG. 3. Again a sprue was created andremoved.

It is within the scope of the invention to provide selected portions ofthe surface of the over-molded thermoplastic elastomer with aappearance-enhancing texture. The texture may be of any appropriate andwell known type. In FIG. 13 and 14, the upper seating portions of theseat and the entire lid are shown provided with textured areas 18 and19, respectively, wherein the surface is of a subtle type which enhancesthe appearance. At the same time, the textured surface 18 and 19preferably allow the user adequate mobility while seated and alsoretained easy cleaning characteristics. It will be understood thattextured areas may be applied to the entire seat and lid surface orselectively as desired or not at all. For decorative purposes some seatsand lids may also be molded with sculpted surfaces. The sculptedsurfaces may be of any appropriate design. In FIG. 15, the top surfaceof lid 2 a is shown provided with one such sculpted area indicated at20.

As stated above, some seats and lids may be made with the hinges moldedas part of the insert and some may use separate decorative hinges madeof metal or plastic for example. An exemplary metal hinge is illustratedin FIG. 16 at 20.

When a seat assembly of the present invention is to be provided withmetal hinges such as cooperating hinge elements 20 a and 20 b (see FIG.16), the hinge elements are provided with perforated flanges 21 a and 21b molded into the inserts providing a secure mechanical bond betweeneach hinge element and its respective seat or lid insert. The over-moldmay also incorporate parts of the hinge. FIG. 16 illustrates a seatassembly 22 a and 22 b of the present invention provided with separatemolded in hinge elements 20 a and 20 b. The hinge elements 20 a and 20 bmay be made of metal, rigid plastic, or any other appropriate rigidmaterial.

To further enhance the flexibility in manufacturing specialized seatsand take advantage of the unique molding process, FIGS. 17 and 18 showchannels 23 that can be incorporated in the reinforced thermoplasticseat inset 1 b to allow for the installation of a low wattage heatingelement or elements 24. The insert with the heating element would thenbe over-molded thereon with the thermoplastic elastomer totally encasingthe heating element. Provisions are made on the over-mold to allow theelectrical cord to exit the mold during the molding process. On thefinished seat the cord would exit the rear of the seat so that it couldbe plugged it to a convenient electrical outlet.

Modifications may be made in the invention without departing from thespirit of it. For example, the teachings of the present invention arealso applicable to toilet seats without lids.

What is claimed is:
 1. A seat assembly for a toilet, said assemblycomprising: a strong, substantially rigid, injection molded seat insertof a first synthetic material; said molded seat insert having a topsurface, a bottom surface and surrounding side surfaces; at least partof said top surface having an injection over-molded layer of a secondsynthetic material to form a finished toilet seat; said over-moldmaterial having a durometer hardness less than the hardness of saiddurometer hardness of said seat insert; said injection molded seatinsert constitutes substantially the bulk of said finished seat; saidfirst synthetic material and said second synthetic material beingchemically compatible so that a chemical bond occurs between saidinjection molded seat insert and said over-mold layer.
 2. A seatassembly for a toilet as recited in claim 1 wherein said first syntheticmaterial and said second synthetic material are both of the samechemical base.
 3. A seat assembly for a toilet as recited in claim 1wherein said first synthetic material includes a reinforcing fillermaterial.
 4. A seat assembly for a toilet as recited in claim 3 whereinsaid reinforced synthetic material comprises fiberglass reinforcedpolypropylene containing from about 1% to about 2% of a foaming agent,said over-mold layer comprising an olefin base thermoplastic elastomericmaterial bondable with said injection molded seat insert, said over-moldsecond synthetic material containing an antimicrobial additive.
 5. Aseat assembly for a toilet as recited in claim 3 wherein said injectionmolded seat insert comprises an olefin base thermoplastic, saidover-mold layer comprising an olefin base thermoplastic elastomerchemically bonded to said injection molded seat insert.
 6. A seatassembly for a toilet as recited in claim 3 wherein said first syntheticmaterial comprises fiberglass reinforced polypropylene, said over-moldlayer comprising an olefin base thermoplastic elastomer chemicallybonded to said injection molded seat insert.
 7. A seat assembly for atoilet as recited in claim 3 wherein said first synthetic materialfurther comprises a fiberglass reinforced, olefin base, thermoplasticmaterial.
 8. A seat assembly for a toilet as recited in claim 3 whereinsaid first synthetic material further comprises a fiberglass reinforcedpolypropylene.
 9. A seat assembly for a toilet as recited in claim 1wherein said over-mold layer comprises a thermoplastic elastomericmaterial with a durometer hardness of Shore D 50 or softer.
 10. A seatassembly for a toilet as recited in claim 1 wherein said over-mold layercomprises a thermoplastic elastomer bondable with said injection moldedseat insert.
 11. A seat assembly for a toilet as recited in claim 1wherein said over-mold layer comprises an olefin base thermoplasticelastomeric material.
 12. A seat assembly for a toilet as recited inclaim 1 wherein said over-mold layer includes an antimicrobial additive.13. A seat assembly for a toilet as recited in claim 1 wherein anappearance enhancing texture is provided in at least selected areas ofsaid seat.
 14. A seat assembly for a toilet as recited in claim 1including hinge elements for said seat, said hinge elements comprisingan integral one-piece part of said injection molded seat insert.
 15. Aseat assembly for a toilet as recited in claim 1 including hingeelements for said seat, said hinge elements being embedded in saidinjection molded seat insert.
 16. A seat assembly for a toilet asrecited in claim 1 including at least one heating element located in agroove in said injection molded seat insert and covered by saidover-mold layer.
 17. A seat assembly for a toilet as recited in claim 1further comprising a lid assembly, said lid assembly comprising: astrong, substantially rigid, injection molded lid insert of a firstsynthetic material; said molded lid insert having a top surface, abottom surface and surrounding side surfaces; at least part of said topsurface having an injection over-molded layer of a second syntheticmaterial to form a finished toilet seat lid; said over-mold materialhaving a durometer hardness less than the durometer hardness of said lidinsert; said injection molded lid insert constitutes substantially thebulk of said finished lid; said first synthetic material and said secondsynthetic material being chemically compatible so that a chemical bondoccurs between said injection molded lid insert and said over-moldlayer.
 18. A method of making a seat assembly for a toilet comprisingthe steps of: (A) injection molding a strong substantially rigid,lightweight seat insert of a first synthetic material, said molded seatinsert having a top surface, a bottom surface and surrounding sidesurfaces; (B) injection over-molding at least part of said top surfacewith an over-mold layer of a second synthetic material having adurometer hardness less than the durometer hardness of said seat insertto form a finished toilet seat; said injection molded seat insertconstitutes substantially the bulk of said finished seat; said firstsynthetic material and said second synthetic material being chemicallycompatible so that a chemical bond occurs between said injection moldedseat insert and said over-mold layer.
 19. A method as claimed in claim18 wherein said over-mold layer comprises a thermoplastic elastomericmaterial with a durometer hardness of Shore D 50 or softer.
 20. Themethod as claimed in claim 18 wherein said over-mold layer of saidsecond synthetic material comprises a thermoplastic elastomer bondablewith said seat insert.
 21. The method as claimed in claim 18 whereinfirst synthetic material comprises a fiberglass reinforced olefin basethermoplastic material and said over-mold layer of said second syntheticmaterial comprises an olefin base thermoplastic elastomer.
 22. Themethod as claimed in claim 18 wherein first synthetic material comprisesfiberglass reinforced polypropylene and said over-mold layer of saidsecond synthetic material comprises an olefin base elastomer, andincluding the step of injection over-molding said insets with saidover-mold material at such temperature and pressure as to chemicallybond said over-mold material to said insert.